Mistake
by Breadcrumbz
Summary: There have been many mistakes made in the life of the consulting detective Sherlock Holmes, but the one he regrets above them all had the greatest impact. Vampire!Sherlock and one-sided Sherlock/John.
1. Chapter 1

**Chapter 1:**

In his entire life as a vampire, there always came a time when he'd have to face the fact that he was a killer. A cold blooded, dead, killer - taking some human's life to prolong his own. It's exactly why he always tried to avoid feeding for as long as possible, to wait until he could break into a nearby hospital and take some nearly out of date blood. Naught but a scavenger. It really sickened him, but whenever he was on cases the hunger could completely hinder his deductions and that was something Sherlock Holmes detested above anything in the world.

Really, the fact he still needed to feed otherwise his work would come to harm was just detestable. It was late in the summer, the constant rain subsiding to make way for a thick and humid air, and Sherlock Holmes had moved towns once more to continue his work as a consulting detective. Rather annoying that he had to stage his death every twenty years (that was always painful to do, especially the physical after effects of being 'more dead' for a day or so), change his appearance and his name just because he couldn't age. He had advanced agility, sight, hearing and smell - oh and let's not forget he was unable to die - but he couldn't _pretend _to age. No. He always had to come up with some dramatic way to end his career, which was always trouble. A trouble which his brother Mycroft wondered why he even bothered with. The elder vampire had a private life in the British government, working in the 'Vampire logistics' department to ensure the general public were unaware of their existence and that other vampires didn't know about other vampires. There were a set number of guidelines the few vampires alive (well, dead if we're being specific) had to follow.

Sherlock always had a tendency to break a few, what with having a high-profile occupation which had him facing humans on a daily basis. Also there was the simple fact that Sherlock became bored easily and constantly needed the praise and attention of everyone in his company. It was a known fact, even to the vampires, that Sherlock Holmes was a genius and he had the ego to match. So it turned out that this summer, Sherlock Holmes (currently living under the name Altamont Yvole - a parting gift from his brother making him spend the next thirty-odd years with a fake Ukrainian accent) was on a trip to the neighbouring countryside of Bath to solve a most interesting case about a pair of murderers who stole the identity of Mr Richard Blake, and then proceeded to kill the only person who was able to identify the victim, Ms Charlotte Janes, and thus pin the murder on him. All in all making off with Mr Blake's fortune from the predominant care-home business in the village.

Needless to say, it was a very engaging case but it had dragged on longer than anticipated and soon he was reminded of the fact he was a vampire. He wasn't about to let a little starvation ruin his case but when he could no longer _think _through the dizziness, he was inclined to find some blood. '_And soon._' Sherlock thought, sagging onto a bench at the local park, his long coat and scarf out of place on the bright day. The visit to the local hospital had proven impossible to steal any blood plasma - the smaller establishments always had better security than the larger ones and stealing regular blood would make him ill - and he was starting to get desperate, tired and perhaps a little manic.

The more that time passed, the more he realised he would have to kill someone, but during his stay he hadn't noticed any homeless in the village so he'd have to hunt carefully. Finding someone who wouldn't be missed, had a dull life and was stressed enough that they would kill themselves (either literally or through a stress-related illness) was what he usually did. It always made him feel less guilty when he hunted carefully. In a village like this, however, it seemed like an impossible task. There was a high number of elderly... but none that he could kill without causing a huge media storm, especially as Mr Blake's care homes had a lot of press at the moment over the murder. Mistakes were best to be avoided. Once he had been pressured into a case to find the person responsible for killing this man suffering from depression - a man Sherlock killed - and it took months to convince others that the man killed himself and that it wasn't a soon-to-be serial killer. Not wanting a repeat of the incident, he needed to make a smart decision on who to take before coherent thought became impossible and he wouldn't be able to control his own instincts.

That was when he saw her sitting under a nearby tree. Judging by her uncomfortable posture, her trendier clothing and the styling of her ash-blonde hair she didn't live in the village. A complete and utter stranger to everyone around her and, judging by the discolouration on her forehead and the skin around her right wrist she worked in an office. A drone - they were rarely missed. The woman was clearly stressed with her work (perhaps the fact her mother was suffering from dementia, too, and could no longer recognise her - yet again more evidence the woman wouldn't be missed) and looked truly done out. This was his chance. A life to continue the case and then save more lives; that was Sherlock's reasoning as he watched the woman and her surroundings carefully. Blending into the few shadows was as simple as breathing, and Sherlock had had years to perfect the art of disguise even with such dramatic clothing.

As soon as the decision was made, Sherlock rounded on the woman and dragged her silently into the nearby foliage before taking her life with a sharp snap. It was a quick death, Sherlock hated to cause people more suffering than they needed, and he promptly drank his fill - the warm liquid feeling like gold on his lips. It was sweeter than usual, which meant the woman had only just eaten, but the metallic tang was a welcomed relief as his thoughts and strength came back to him. The woman fell stiller in his arms. It would be no more than five minutes later that Sherlock Holmes realised his mistake and would stop at nothing to take it back, to repair what he'd done, but it was too late. The woman had stopped breathing and her skin was clammy and growing colder by the second to mirror Sherlock's own skin. Dead. She would never come back.

John Watson was 7 when his mother was murdered. It had been a beautiful day in August when she decided to take him and Harry to visit her mother, who had been slowly growing more and more demented much to the boy's aggravation. The young boy hated visiting his grandmother as she always called him Silvia (John had no idea who she was but he was certain he looked nothing like a girl did) and there were no other children there. Today had been his friend Joseph's birthday party and he had been invited, but his mother insisted they both tag along - Harry was 16 at the time and had been more than thoroughly annoyed she couldn't spend the day at a Blondie concert with her friends.

If John had succeeded with persuading his mother not to go visit, then perhaps none of this would have happened and the world would have been a much more different place. Perhaps in another universe John had convinced his mother not to go and she would still be alive. They went, however, and there was no changing that. The slumbering countryside village never seemed to change and remained in a constant static: a dull stone surrounded by bright and shining ones determined to never change. John could see how his grandmother was going insane here, it was just so quaint and boring that as soon as their car entered it, the young boy had sat having a tantrum. Harry just looked unimpressed, but after seeing that a local music fair was going on at the park she begged to go see it.

Their mother agreed, as long as the agonizing visit to their grandmother's happened first. It seemed like an age they were at that house, and the newly-named Silvia and Harry were allowed to go to the park - Harry going off to the fair straight away and John staying nearer his mother, unsure of the older teenagers attending. "Go along and have fun, Johnny dear, I'll be right here watching." His mother had smiled to him, as she shooed him lovingly off towards a nearby fountain. Giggling to himself, John ran over and proceeded to catch invisible fish in the fountain. The cool water was a welcoming relief to the warm day and it didn't seem so bad to be at the dreary village anymore, as fishing was just too fun.

Little did he know that those words were the last ones he would get from his mother. An hour or so later his stomach interrupted his game with a loud grumble and he wondered if mummy would let him go to that cafe again to get some cheese and onion pasties. On his way back to the tree his mother had been at, he was shocked to see she was no longer there. Was she hiding from him? John was good at hide-and-seek but he didn't know mummy was playing it at the time. Either way, he decided to start looking for her as his stomach really was rumbling.

"Mummy? Come out, come out wherever you are!" A small voice had called from nearby, and Sherlock peered around the edge of a tree to see where it had come from - a small sense of dread prickling the back of his neck. It was a young boy, about the age of 7, who was looking around a nearby tree with a determined look on his face. A tree which the woman who was now lying dead before him had been sat at moments ago.

Shit.

It didn't take a genius to tell what had just happened and it took all his willpower not to throw up. A child. The woman had a _child_. How had he not noticed that? The stress had come from looking after him, not from her work! He was so stupid, of course no one was going to get stressed working in an office. The boy walked in his direction, growing a little more confused now, and Sherlock swiftly hid behind some trees to await the horrible moment the boy saw his mother dead. Not just dead, but covered in _blood._ Her blonde hair turned a rusty colour as the metallic smell permeated through the damp air. The foliage nearby was splattered in red at sharp angles and contrasted to such a violent degree. Danger, wild, savage. It was everything he was running from laid out in front of him for the world to see and it made him want to run faster but he _had_ to see this. Had to remind himself. He could hear his brother's words in his head: '_Caring is not an advantage, Sherlock. Humans don't care about their food after all._' Sometimes he felt like the only vampire who did care, even if he denied it. The few he had met through Mycroft saw humans as just food and considered farming them. It was disgusting, and Sherlock couldn't take his eyes off of the scene he'd just caused. One step, two step and the young boy was stood over the body of his mother, frozen in place. The look of determination crumbling into something painful, stiff and ever-so-vulnerable as the first of many tears began to form in dark grey eyes. Small legs gave out a moment later and the boy plummeted.

He sat there, clinging to his mother and whimpered her name over and over again. This was wrong. This woman was meant to have no one, yet she had a child... Whoever this young boy was, Sherlock had just destroyed his life and the thought of that alone caused his throat to clench up, let alone the sight of the boy. He really did feel like being sick, to take back everything he'd just done, but it was impossible. Sherlock knew that much - he dealt with life and death on a regular basis. He'd seen families cry over their loved ones they could never get back, children too, and had never understood the sentiment. But this was different. It was like someone had stabbed him low in the stomach and wrenched the knife so the wound couldn't heal. It would only become infected and fester with time.

When other people found the boy and his mother, he knew it was time to leave.

John Watson was 7 when Sherlock Holmes murdered his mother.


	2. Chapter 2

**Chapter 2: **

He couldn't believe how stupid he'd just been, how he'd not even realised that the woman had a child. Well, as he learnt later from Detective Inspector Langdon, the woman actually had two children: the young boy and a daughter. Sherlock couldn't believe how much of an idiot he was for making a mistake and it tore away at him due to the fact Sherlock Holmes did not make mistakes, he wasn't designed to. It might have been suspicious taking this much interest in the woman's murder - more specifically her children - but Sherlock needed to know. He needed to know whose life he'd ruined, so he headed straight to the police station after cleaning himself up.

"What's the boy's name?" Sherlock asked in his usual languid way. Langdon, briefly confused about why someone as cold as Altamont Yvole would even be interested, flicked through the file in front of him. Detective Inspector Langdon was middle-aged, the sides of his auburn hair turning a bright white with his eyes resting in deep-set wrinkles. He'd worked most of his life behind a desk and his slightly hefty figure displayed it clearly, a patchy moustache tinged yellow from his cigarettes was the icing on the cake. His suit, which was old-fashioned now in 1981, had become slightly discoloured from years of smoke and Sherlock mused that the cut was odd as well, almost as if the man's mother had made it.

"Uh, his name's John Watson." He said in a cherub-like voice, a heavy Welsh accent adorning his words. "Why?"

Sherlock just ignored his question. "Do you know what's going to happen to him? His grandmother's unable to look after him. Any other family?" This time Langdon placed Sherlock under a scrutinising stare. Ah, of course. He'd only been familiar with Sherlock's methods a few months now, so he wouldn't be comfortable with him speaking his deductions like common knowledge. It was still the awkward period where he'd have to explain everything to the idiot detectives. Sherlock would have hoped that after around a century of his work, detectives would eventually get a clue. "Isn't it obvious? The reddening on her hands show she had been pushing a wheelchair around and she smelt strongly of a particular brand of disinfectant, but was obviously not using it herself due to it being an industrial product. You can tell she's not a cleaner just by looking at her hands and clothing. It just so happens the disinfectant is used almost daily at the retirement home not far from here. Judging by the woman's age, and the fact she's visiting from out of town, her mother's suffering from dementia at this particular establishment."

That seemed to settle the detective down and he looked up the answer to the previous question almost begrudgingly. It only made the reality of the situation settle low in the vampires stomach. This wasn't the first woman Sherlock had killed, oh no, but this was the first mother he'd killed. His heart sank when Langdon spoke. "Nope. Nothing. They're going to be put into an institution until they're adopted or the eldest - Harry I think her name is - is old enough to look after them both."

Sherlock paled.

This was worse than he thought. He really _had _screwed up. He'd really ruined this boy's entire life. His fault, his fault, his fault. What could he do to fix it? There had to be a way to fix his mistake - there was always a solution and it alarmed him to realise that perhaps he couldn't fix this one. As he grew more and more frantic, Sherlock felt the need to distance himself from everyone. When the static noise and typing and plain human noise became unbearable, he stormed out of the police station and headed straight back to his hotel. Leaving a letter to explain who the murderers were, how they'd done it and where they could find them didn't make it any better and in fact only made him feel confined. He'd caught the killers, that should have made him ecstatic, but the boy's weeping face kept crawling into his consciousness and he couldn't help but notice the awful bureaucracy.

When he entered his room, he wasn't surprised to find his brother there as the embodiment of yet another bureaucracy he despised. '_Always sticking your nose into everyone's business, it seems._' The glare he shot in greeting didn't unnerve Mycroft in the slightest, he was used to it ever since 1891, as he sat in one of the chairs next to the sofa with tacky upholstery. The elder Holmes simply smirked with the corner of a thin lip, most likely finding the whole idea of Sherlock screwing up highly amusing despite the paperwork that would come from it.

"Take a seat, Sherlock." Mycroft gestured to the seat opposite him and spoke in a firm tone of voice. He knew his brother wouldn't take the seat and to prove that fact Sherlock made no notion to move towards it, folding his arms in an attempt to make Mycroft just get on with it. Mycroft always did wonder when his brother would forgive him, especially as Sherlock should be grateful not resentful. "I assume you know why I'm here." A pause as he took in the sight of the vampire before him (he believed the pause added to the dramatic nature of the discussion). "How are you taking it?"

"I think that's none of your business." Sherlock snapped, his glare darkening. "Now that you've asked your question I think you can find the door." The way his voice sounded, so gritty and raw, made it obvious how he was taking it. His snarl was displaying the base of a porcelain fang, which was unusual for the detective as only turmoil with his emotions would render him in such a state. Oh, indeed there was turmoil. He'd completely _destroyed _someone's life because he was nothing but a disgusting, blood-sucking leech and right now he wanted Mycroft to disappear forever. If the latter were honest, Mycroft would say he was even a little puzzled his brother was taking it this badly. He'd never cared as a human, after all, perhaps...

"Why are you so concerned for the human boy? It's unlike you."

"I don't care about the boy." His lifeless heart clenched, did he really care about the boy so much? When he replayed the noise of the boy's crying back in his brain, the churning in his stomach proved something he would rather deny. If he were lucky, Mycroft wouldn't notice. "I'm just irritated this was more hassle than it needed to be. Now if you don't mind, Mycroft, Altamont here has to solve another case." Pale eyes leered at the older vampire when the name 'Altamont' was spoken. That had been plain childish and Sherlock planned to kill off Altamont sooner than his usual names, if only to rid himself of the ridiculous accent. As always, Mycroft could see through him. He was probably the only person who could see through Sherlock and know what he was going to do next, even if that was rare with the erratic vampire.

It seemed this time, however, he knew what was going to happen next before Sherlock himself knew and pursed his lips ever-so-slightly in disappointment. Surely his brother knew that simply could not work? Why would a human boy get to him, a heartless vampire, this much? It was a little nauseating how such a creature could get to the genius that was his brother. Either way, it was his sworn duty to remind Sherlock of a few certain rules he had to follow before he made it any worse. For both parties involved.

"You do realise, that for the benefit of all vampires, you have a sworn duty to follow society's rules." Sherlock quirked a brow at him from the sudden recital of the rules, but Mycroft continued without giving the younger Holmes a second glance. "Rule one: don't tell humans that you're a vampire. You're doing fine with that one. Rule number two: you are not to befriend a human. Rule number three: you cannot marry a human or move in with a human." Sherlock rolled his eyes now, letting out a throaty protest. It's not like he was an idiot - his brother had written these rules so of course he knew about them. Mycroft, as he was so demonstrating, never shut up about them. If this was a stab at him breaking one of the rules unintentionally, he'd throw Mycroft out there and then.

"Yes yes yes, and rule number four is that I can't turn a human and the next one is that I need to take care when it comes to feeding. I get it. I made a mistake. So if you could leave already I would very much appreciate it." Mycroft shook his head but stood up anyway.

"I'm afraid you missed a few. One in particular I will not allow you to break, even under the current circumstances." Sherlock continued glaring. He really didn't care. He could break these invisible rules if he wanted to - they would only lead to his own death. The world wasn't as suspicious as it had been in medieval times, vampires were more-or-less able to control their feral urges if they steered clear of humans (really, Sherlock had strong willpower for a vampire despite his mistake), and there would be no repeat of the mass-killings. Vampires had learnt to sedate their prey and feed regularly to control themselves; humans had become dim-witted and prone to ignorance. They believed vampires to be fairy-tales and fairy-tales they would remain so long as Mycroft Holmes remained in power. Seeing as he wasn't going to get a reply from Sherlock, Mycroft elaborated. "Rule number _four_," He stressed the word to show that Sherlock had in fact missed one, not that the younger cared about getting the order wrong. "Is that you cannot, under any circumstances, Sherlock, adopt a human child."

Perhaps that one had slipped his mind, but of course Sherlock wasn't going to break that rule! Ridiculous! How could he do that? Look after a child when he knew barely a thing about humans? He'd kill him in days. Plus, how would he explain how he wasn't ageing. '_Or, I don't know, that I killed his mother._' Sherlock scowled at Mycroft as though he was the idiot he was imitating. There was no way that would have worked, why was his brother always jumping to the wrong conclusions?

"Just get out. You know I would never adopt a _child_, Mycroft." He hissed, motioning to the door. Mycroft shook his head as he left. His brother was always so stubborn about it, but he knew he must have cared somehow. Why else would he solve how people died? It was hard not to be concerned about the vampire's well being when he knew that Sherlock could easily make it worse at this point.

It wasn't until the evening that Sherlock recognized why Mycroft had reminded him of that particular rule. His mistake, that child, the tears on his face. Everything. They'd all built up tensions within until they exploded - the fragile seams of sanity coming apart. The vampire was curled up on the sofa at the hotel, his knees tucked tightly under his chin with the lights turned off - the only light coming from the moon who crept through the crack in the window. He was dressed in his usual clothing when it had just hit him. The most unrelenting and painful guilt he had ever experienced in his 90 years as a vampire was tearing his insides to shreds, and he automatically needed to fix it, needed to make it right. All because he was nothing but a vile vampire giving into his instincts, he'd destroyed a boy's life. Took the most precious person the boy would ever know away from him prematurely.

Straight away his mind told him to adopt the children, but he knew Mycroft would be more than upset at the idea if he had specifically told him not to do it. Not that he was worried about what punishment Mycroft could come up with (Sherlock felt like dying and the offence wasn't even serious enough for that - that privilegebelonged to those vampires who did lose themselves entirely to their instincts and became feral, and Sherlock didn't want to even _feign_ being feral to end it), but Mycroft's words had a practical aspect to them. He'd ruin the children's lives more if he adopted them, he knew that much... There had to be some way to stop this hole from getting any deeper, to stop his heart from tearing in two. The thought of having a heart made it ten times worse - it'd been made of stone since his... best friend died a human death, so for it to be breaking for a second time was devastating.

Then the idea hit him. Of course, it wouldn't make the situation any better but he had to do _something _for the child. Anything. He couldn't handle this grief for another day if it kept him refined to corners of rooms. In fact, Sherlock wouldn't put it past himself to behave more drastically to get rid of guilt for even a moment, so this was a plausible option. This wasn't too bad - he wasn't breaking Mycroft's precious rules after all and, well, he didn't know what else to do. Seeking comfort from his plan, Sherlock eventually managed to slip into a fitful sleep where he had curled up and awoke the next morning with the whispers of his decision still floating in the room and dried tears on his cheeks. The sleep really hadn't helped clear his mind or give him the energy for the day, but at least he could start on distracting himself. The world was only a long chain of distractions when he was alive, which hadn't changed after death. It was a daily reality, now, and adding another thing to the list of torments made the need for a distraction all the more vital.

Sherlock Holmes soon discovered he was on his way to one of Bath's institutions, having glanced over the name whilst Langdon fumbled through case papers. He really should have been working on clearing his - well Altamont's - innocence but the people of the village were so sleepy he would get away with it, especially if there were no more murders. The vampire might have been half-starved at the time of his mistake but he was still precise enough to get away with it and the thought of blood still made him indisposed.

With the mistake already chasing after him, Sherlock decided he was going to watch the boy almost as a guardian. His work could wait - there was no way they would work as a distraction at the moment. It had been easy to sneak into the place, sticking to the shadows that filled most of the hallways. He could hardly imagine such a child, so bright and full of energy, living in a place like this. Would he fit in? The whole idea seemed unlikely and it only served to cause the knife in his stomach to dig in deeper.

Maybe watching over him would lessen the pressure? Sherlock was nearly at the stage of pleading, he was that desperate. It wasn't long until he found the boy (his name was John and Sherlock had heard the boy's mother calling him in for dinner amongst a few of the many vivid dreams the previous night) sat in his room looking out of the window. The stool he sat on looked as worn out as the cotton sheets draped over the bed, and Sherlock wondered briefly if John's slight weight would cause it to collapse. He supposed looking out the window was a successful escape from damp walls and overly cheerful toys; particularly, Sherlock noted, the clown with a distorted smile John could only hope to mimic. Seeing the boy made the urge to flee worse but the vampire knew he deserved it and couldn't cower away from what he'd done - he had to take responsibility.

Obviously, making contact with the boy would be against the rules so he simply observed. The boy's posture was ramrod straight and guarded, his eyes lifeless and face clear of all emotions in an attempt to keep control over himself. He'd cried the entire night without anything changing so he decided to move on and ignore it; his father had left them years ago and John was fairly used to losing people. It was like his dog, Kit. John spent all his time with that dog, would care for it and even let it share his bed, but one day his dad told him he'd run away. John knew now the dog had died, was as dead as his mother, and it left an emptiness he couldn't control. Everything he felt seemed shallow, but he had to try right?

It takes a month for John to start settling into the institution and its routines, along with getting along with the other children there. Throughout that time, Sherlock Holmes does not take on another case and continues to watch the child, his feelings improving when John finally befriends a boy by the name of Frank Armstrong (a young boy with light brown hair, warm brown eyes and rose-tinted cheeks dusted with freckles) and the first smile crosses his face. It's not a real smile, Sherlock can tell that much when it comes to humans, but at least the boy is trying to move on as he's a strong one and that makes everything slightly more bearable. If he doesn't give up, then he's certain John will be fine and the thought of John coping with his mother's death gives Sherlock some well-needed comfort. Though Sherlock's certain the hole John's mother left will never improve, it will never be enough, and in the end he's just deluding himself.


End file.
